Art of combustion and steam generation



April 19, 1932. YE. LUNDGREN ART OF COMBUSTION AND STEAM GENERATION Filed Jan, 20, 1925 3 Sheets-Sheet IN VEN TOR ATTORNEYS A ril 19, 1932.

E. LUNDGREN ART OF COMBUSTION AND STEAM GENERATION 1925 3 Sheets-Sheet 3 Filed Jan. 20

III I llllL 'INVENTOR M M B Y V ATTORNEY Patented Apr. 19, 1932 UNITED STATES PATENT OFFICE EDWIN LUNDGREN, F FREDERICK, MARYLAND, ASSIGNOR TO COMBUSTION ENGINEER- ING CORPORATION, A CORPORATION OF NEW YORK ART OF COMBUSTION AND STEAM GENERATION Application filed January 20, 1925. Serial No. 3,552.

This invention relates to the art of combustion and the generation of steam, and is especially useful where ulvei'ized coal, oil or gas is used. In some 0 its aspects the invention has to do particularly with the burning of finely divided fuel in suspension.

The successful applications of burning pulverized fuel have heretofore been made in conjunction with commercially known types of boilersan inheritance of design suitable for the burning of fuels on grates, stokers and the like in which connection large and expensive combustion chambers have been employed.

One of the primary objects of this invention is to provide a boiler suitable to the burning of pulverized fuel, and especially an ar rangement suitable to the novel method of burning such fuel herein described. In this connection I aim to produce a compact selfcontained steam generating unit, in which the principles and requirements of steam raising and combustion of pulverized fuel have been properly correlated,

A further object is to secure both high capacity and high efficiency.

Still another object is to provide an improved boiler capable of withstanding high pressures, say, for example, 1200 to 1500 pounds or more per square inch.

Still another object of the invention is to provide a combustion furnace, the combustion space of which is totally-or at least largelyenclosed by steam evaporative surfaces, whereby, among other things, the usual furnace construction may be dispensed with, and a simple insulating sheathing substituted for the refractory walls.

It is also an object of the present invention to secure and maintain proper combustion of the pulverized fuel in a combustion space defined by such evaporative surfaces.

My invention also contemplates the introduction of the fuel and its burning under pressure, i. e., a pressure higher than the at mosphere.

Another object of the invention has to do with improvements in the manner of the admission of' combustion air.

.The foregoing, together with such other objects as may hereinafter appear, or are incident to my invention, are realized by the improvements now to be described.

A preferred form of the apparatus which I employ in carrying outlmy invention is illustrated in the drawings whereof Fig. 1 is a vertical section thru a boiler embodying my invention;

Fig. 2 is a section taken on the line 2-2 of Fig. 1, drawn on an enlar ed scale;

Fig. 3 illustrates a detail 0 the invention;

Fig. 4 illustrates another detail of the invention; and

Fig. 5 is a fragmentary section of another form of the invention.

Referring now to the drawings, it will be seen that the boiler has three upper drums, 1, 2 and 3, and three lower drums 4, 5 and 6, and a steam drum 7, located above the upper drums. A pair of spaced-rows of vertical tubes 8 and 9, connect drums 1 and 4 and a similar pair of spaced rows of vertical tubes 10 and 11 connect the drums 2 and 5. A row of tubes 12 connect the drums 3 and 6. The tubes 8, 9, 10, 11 and 12 are preferably of the same size and construction. A bank of smaller tubes 13, fairly widely spaced, connect the drums 3 and 6,'also. Rows of cross tubes 14 connect the upper drums and rows of cross tubes 15 connect the lower drums.

Tubes 16, similar to the tubes 8, 9, 10 and V 11 connect each end of the drums 1, 2 and 3 with the ends of'the corresponding drums 4, 5 and 6.

' It will be seen from the foregoing that the tubes 9, 10, 11, 12 and 16 divide the enclosing chamber 17 into two vertical combustion spaces A and B. These tubes in effect constitute walls defining the combustion space to which end such tubes are preferably provided with fins 18 (see Figs. 1 and 3).

ubes 16 in Fig. 1 are not shown provided with such fins for the reason that the figure would be confused if they were indicated. The tubes 9 preferably have the fins for approximately their full length; the tubes 10 and 11 and also 12 have thefins extending only part way of their length; and the tubes '8 are similarly provided with fins ex-- tending for approximately their full length.

The fins on the tubes 10 and 11 terminate above the drum 5 so that the two combustion spaces A and B communicate with one another. The tubes 14 and 15 respectively close, or rather define, the upper and lower ends of the combustion space, there being an ash pit C beneath the drums 4, 5 and 6 and the tubes 15.

The tubes. 8 and the tubes 16 preferably have their fins overlapping as indicated in Fig. 4 so as to provide a substantially imperforate wall- The tubes 9, 10 and 11, however, are so spaced that there is a gap between fins of adjacent tubes as shown in Fig. 3, the purpose of which will hereinafter appear. The fins on the tubes 12 preferably overlap as shown in Fig. 4. i

The powdered coal, preferably with carryair, is introduced to the roof of the primary combustion chamber A vertically downward by means of a row of burners D, and air under pressure and preferably preheated is supplied each burner around the nozzle thereof so as to surround the entering coal stream of'each burner, by means of a fan or fans E.

The upper portion of the combustion chamber A is lined with a refractory lining 19 so as to subject the incoming fuel to radiant heat for ignition purposes.

By reason of the introduction of the coal and air under pressure, there is very intimate admixture taking place promptly with the result that ignition also takes place promptly. However, only a port-ion of the air required for combustion is introduced with and around the entering fuel. This is known .as the primary air for combustion. The balance of the air required for combustion (known as secondary air) is supplied in the following manner.

It has heretofore been noted that the tubes 8 and 9 and the tubes 10 and 11 are spaced apart and it follows from this and the provision of the fins that these tubes provide chambers F and G. Air which has been preheated by passage thru the air heater H, subject to the heat of the waste gases, is introduced in to the chambers F and G by the casings I 20, the supply of air being controlled by the dampers 21 and 22. This air introduced to the chambers F and G is under pressure, a Variable speed fan I being provided for this purpose. The air entering the chambers F and G passes out into the combustion space in vertical sheets thru the gaps between the fins 18, as shown in Fig.3.

In consequence of admission of air in this manner, intimate'admixture takes place and all particles are insured of being supplied with the necessary amount of oxygen for their combustion as they progress thru the combustion space.

By locating dampers 23 within the air chambers, control of the amount of air admitted at various levels can be obtained. I

The control afforded is such as to enable proper combustion to be carried on at various rates of operation.

Since the boiler is practically all subject to radiant heat, it absorbs a very great quantity of heat and in proportion to its size has an exceedingly large capacity. By virtue of the large absorption of heat, there is a tendency to lower furnace temperature and there fore the relation of evaporating surface to the rate of fuel feed and the rate of travel thru the combustion space are so correlated that, under general operating conditions, the waste gases carry sufiicient heat for the abstraction and return of the needed amounts of heat to properly maintain combustion. Thus the chilling effects of the boiler on combustion are obviated.

As previously poi'nted out, I prefer to operate with the pressure in excess of atmospheric. and the fuel and flame stream is forced from the primary combustion chamber A to the secondary combustion space B.

Combustion, however, is completed within the combustion space and the gaseous products pass into the economizer section, represented by the tubes 13, which are baffled so as to give a downward and then an upward pass to the stack. Inasmuch as combustion has been well carried forward within the primary combustion space A, not so much air is needed Within the combustion space B, and, therefore, in the arrangement shown, I introduce less air into the latter combustion spacev I locate superheater elements 24 in the up per part of the combustion space B and secure a high degree of superheat.

Feed water is supplied thru the pipes 25 and 26.

The tubes 15 are spaced sufficiently far apart to permit the refuse 'particles to freely pass therebetween into the ash space C, from which the ash is removed.

It will be observed that the arrangement is such that even tho operations be conducted at a pressure higher than atmospheric, the enclosing shell or chamber is fully protected.

By operating under pressure higher temperatures may be achieved, which in itself minimizes the chilling effect of the tubes in so far as proper combustion is concerned.

In consequenceof the higher temperatures and also of the higher rate of heat absorption of the tubes, it will be seen that high capacities may be realized from a small installation.

The tube arrangement is such that large ligaments are provided at the drums in consequence of which I am enabled to operate at high boiler pressures.

The two combustion spaces are of restricted horizontal depth and the installation, as ,a whole, occupies less space, horizontally and vertically, than do installations of present standard practice of the same capacity.

. In the arrangement of Fig. 5, the ash pit isof difierent construction and has air cooled hollow walls; and the economizer section has ts passes arranged so that the offtake is from a low region, bringing the air heater down and making it possible to carry the air heater blower on the boiler room floor.

I claim:

1. In combination, a chamber, two groups of boiler .tubes defining combustion space, said groups each consisting of two spaced rows of tubes, and means for introducing combustion a r to the spaces between rows for flow to the combustion space.

2. In combination a chamber, two groups of boiler tubes defining combustion space, said groups each consisting of two spaced rows of tubes, and means for introducing combustion air to the spaces between rows under pressure for flow to the combustion space. a

3. In combination a chamber, two groups of boiler tubes defining combustion space, said groups each consisting of two spaced rows of tubes, and means for introducing combustion air to the spaces between rows under pressure for flow to the combustion space, together with means for controlling the air supply.

4. In combination, an enclosing chamber, a pair of upper drums, a pair of lower drums, two spaced rows of tubes connected to each pair of drums. the drums being so located that a combustion space is provided between the two groups of tubes, means for supplying fuel, and means for supplying a r for combustion through the space between the rows.

5. In combination, an enclosing chamber, three upper drums, three lower drums, tubes connecting respective drums, the drums and tubes being arranged to provide two substantially vertical, communicating combustion spaces w th the tubes exposed to radiant heat, a bank of tubesat one side of the second space, bafiiin'g for the said bank of tubes, and means for supplying fuel to the first space.

6. In combination, an enclos ng chamber, three upper drums, three lower drums, tubes connecting respective drums, the drums and tubes being arranged to provide two substantially vertical, communicating combustion spaces with the tubes exposed to radiant heat, a bank of tubes at one side of the second space, baffling for the said bank of tubes, and means for supplying fuel to the first space together with cross connecting tubes for the lower drums. I

7. In combination,- an enclosng chamber, three upper drums, three'lower drums, tubes connecting respective drums, the drumsand tubes being arranged to provide two substantially vertical, communicating combustion spaces with the tubes exposed to radiant heat, a bank of tubes at one side of the second space, bafliing for the said bank of tubes, and means for supplying fuel to the first space together with cross connectingtubes for the lower drums and the upper drums.

8. In combination, an enclosing chamber, three upper drums, three lower drums, tubes connecting respective drums the drums and tubes being arranged to provlde two substantially vertical, communicating combustion spaces with the tubes exposed to radiant heat, a bank of tubes at one side of the second space, bafliing for the said bank of tubes, and means for supplying fuel to the first space together with cross connecting tubes for the upper drums. v i

9. In combination, an enclosing chamber, three upper drums, three lower drums, tubes connecting respective drums, the drums and tubes being arranged to provide two substantially vertical, communicating combustion spaces with the tubes subject to radiant'heat, a steam drum above the upper drums, and connections therebetween, together with a superheater device subject to radiant heat connected with the steam drum and located in the second space. I

10. In combination, a boiler having a plurality of upper and of lower drums, substantially vertical tubes connecting the drums and defining combustion space, means for admitting fuel in finely divided form together with primary air for combustion. means forming a s ace behind the tubes, and means for admitting further air to said space, the tubes being spaced apart to provide a plurality of air openings.

11. In combination, a boiler having a plurality of upper and ofv lower drums, substantially vertical tubes connecting drums and defining combustion space, means forming a space behind tubes, and means for admitting air to said space, the tubes being provided 'with fins and being spaced apart to provide a plurality of air openings.

12. In combination, an enclosing chamber,

three upper drums, three lower drums, tubes connecting respective drums, the tubes being. arranged to provide two substantially vertical communicating combustion spaces with the tubes subject to radiant heat.

13. In combination, an enclosing chamber, three upper drums, three lower drums, tubes connecting respective drums, the tubes being arranged to provide two substantially vertical communicating combustion spaces with the tubes subject to radiant heat, means for admitting fuel downwardly in one division, and means for withdrawing the products of combustion from the upper part of the other division.

14:. In combination, an enclosing chamber, three upper drums, three lower drums, tubes connecting respective drums, the tubes being arranged to provide two substantially vertical communicating combustion spaces with the tubes subject to radiant heat, means for admitting fuel downwardly in one division, and means for withdrawing the products of combustion from the upper part of the other division, together with means for admitting I combustion air to both divisions.

15. In combination, an enclosing chamber, three upper drums, three lower drums, tubes connecting respective drums, the tubes being arranged to provide two substantially vertical combustion spaces communicating at the lower part but above the middle of the three lower drums.

16. In combination, an enclosing chamber,

I three upper drums, three lower drums, tubes connecting respective drums, the tubes being arranged to provide two substantially vertical communicating combustion spaces with the tubes subject to radiant heat, and a row of economizer tubes also connecting one of said upper drums with one of said lower drums and subject to the gaseous products of combustion. a

17. In combination, a combustion chamber, the vertical walls of which are defined by rows of boiler tubes, a pair'of upper drums into which the upper ends of the tubes are connected, a pair of lower drums into which the lower ends of the tubes are connected, tubes connecting the drums of each pair, said latter tubes also defining combustion space, and means for admitting fuel into said chamber.

183 In combination, a long narrow combustion chamber, the Vertical side walls of which are defined by rows of boiler tubes, an upper and lower drum into which the tubes of one of the .side walls are connected, an upper and lower drum into which the tubes of the other side wall are connected, the vertical end walls of said chamber also being defined by boiler tubes connected into the upper and lower. drums, a row of tubes connecting the two up er drums, a row of tubes connecting the two lower drums, said rows of tubes also defining combustion space, and means for admitting fuel into said chamber.

In testimony whereof, I have hereunto signed my name.

EDWIN LUNDGREN. 

